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Modelling the impact of climate change on rangeland forage production using a generalized regression neural network:a case study in Isfahan Province,Central Iran

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Journal of Arid Land 2017年第4期9卷 489-503页

作者： Zahra JABERALANSAR mostafa tarkesh Mehdi BASSIRI Saeid POURMANAFI Department of Natural Resources Isfahan University of TechnologyIsfahan 84156-83111Iran

Monitoring of rangeland forage production at specified spatial and temporal scales is necessary for grazing management and also for implementation of rehabilitation projects in rangelands. This study focused on the capability of a generalized regression neural network（GRNN） model combined with GIS techniques to explore the impact of climate change on rangeland forage production. Specifically, a dataset of 115 monitored records of forage production were collected from 16 rangeland sites during the period 1998–2007 in Isfahan Province, Central Iran. Neural network models were designed using the monitored forage production values and available environmental data（including climate and topography data）, and the performance of each network model was assessed using the mean estimation error（MEE）, model efficiency factor（MEF）, and correlation coefficient（r）. The best neural network model was then selected and further applied to predict the forage production of rangelands in the future（in 2030 and 2080） under A1 B climate change scenario using Hadley Centre coupled model. The present and future forage production maps were also produced. Rangeland forage production exhibited strong correlations with environmental factors, such as slope, elevation, aspect and annual temperature. The present forage production in the study area varied from 25.6 to 574.1 kg/hm^2. Under climate change scenario, the annual temperature was predicted to increase and the annual precipitation was predicted to decrease. The prediction maps of forage production in the future indicated that the area with low level of forage production（0–100 kg/hm^2） will increase while the areas with moderate, moderately high and high levels of forage production（≥100 kg/hm^2） will decrease both in 2030 and in 2080, which may be attributable to the increasing annual temperature and decreasing annual precipitation. It was predicted that forage production of rangelands will decrease in the next couple of decades, especially

关键词： rangelands forage production climate change scenario generalized regression neural network Central Iran

Evaluation of the efficiency of irrigation methods on the growth and survival of tree seedlings in an arid climate

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Journal of Arid Land 2020年第3期12卷 495-507页

作者： Zahra JAFARI SayedHamid MATINKHAH Mohammad R MOSADDEGHI mostafa tarkesh Department of Natural Resources Isfahan University of TechnologyIsfahan ***Iran Department of Soil Science Department of AgricultureIsfahan University of TechnologyIsfahan ***Iran

Scarce and scattered precipitation in arid regions is detrimental for newly planted *** is essential to provide required water storage for seedlings in restoration projects in the first year of their *** subsurface irrigation can be much more effective than the surface irrigation because of the regulation of water availability and reduction in water *** studied the effect of surface and subsurface irrigation methods on the growth and survival of four common tree species including heaven tree(Ailanthus altissima(Mill.)Swingle),China berry(Melia azedarach L.),white mulberry(Morus alba L.),and black locust(Robinia pseudoacacia L.)by installing underground clay reservoirs with different permeabilities in Isfahan City,*** amounts of animal manure and wheat straw were mixed with clay fraction and cooked in a pottery kiln at 900°C to produce reservoirs with different *** experimental treatments consisting of irrigation and tree species were considered with a factorial arrangement in a completely randomized design with three replications in 2016 and *** water potential of seedlings,which is indirectly related to drought resistance,was measured by a portable pressure *** results showed that saplings height,basal diameter,number of leaves,chlorophyll content and stomatal conductance were significantly(P0.05)affected by the irrigation methods and different permeabilities of clay *** clay reservoirs with low and medium permeabilities constantly provide better conditions for plant growth,and water with lower pressure and longer time intervals to the plant roots as compared with the reservoirs with high *** of variance of the data showed that year and interaction between year and permeability of reservoir had si

关键词： subsurface irrigation clay reservoirs permeability restoration arid area

Investigation of rangeland indicator species using parametric and non-parametric methods in hilly landscapes of central Iran

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Journal of Mountain Science 2019年第6期16卷 1408-1418页

作者： Asiyeh SHEIKHZADEH Hossein BASHARI mostafa tarkesh ESFAHANI SayedHamid MATINKHAH Mohsen SOLEIMANI Department of Natural Resources Isfahan University of Technology

This study aimed to identify indicator species and explore the most important environmental and management variables contributing to vegetation distribution in a hilly upper dam landscape in Zagros Mountain chain, Iran. A stratified random sampling method was used to collect topographic, edaphic, management and vegetation data. The density and cover percentage of perennial species were measured quantitatively. Indicator species were identified using the two-way indicator species analysis. Besides calculating physiognomic factors in sample sites, 24 soil samples were collected from 0 to 30 cm of soil depth and analyzed in terms of gravel percentage, texture, saturation moisture, organic matter, pH and electrical conductivity in saturation extract, lime percentage, soluble calcium and magnesium, available phosphorus, Cation Exchange Capacity(CEC) and soluble sodium and potassium. Multivariate techniques including Canonical Correspondence Analysis and Multi-Dimensional Scaling were used to explore the relationships of species with environmental and management variables. Seven plants were identified as indicator species due to being significantly correlated with management(grazing or non-grazing) and edaphic variables such as CEC, soil texture, pH, CaCO3 percentage and physiographic variable including slope, elevation, and convex and concave formations(p < 0.05). Overall, overgrazing and its subsequent effects on soil characteristics, loss of vegetation cover and trampling were found as the major causes of deterioration. Sustainable and integrated management practices such as the implementation of appropriate grazing systems were suggested to enhance soil quality and reduce the accelerated erosion in upper dam zones.

关键词： Ordination Two-way indicator species analysis Grazing management Ecological amplitude Exclosure

Potential habitat modeling for reintroduction of three native plant species in central Iran

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Journal of Arid Land 2015年第3期7卷 381-390页

作者： Elham G ARDESTANI mostafa tarkesh Mehdi BASSIRI Mohammad R VAHABI Department of Natural Resources Isfahan University of Technology

Potential habitat modeling of endemic species is an appropriate method to maintain biodiversity,ecosystem function and rehabilitation of rangeland *** caragana,*** and *** are endemic in Iran＇s rangelands and some neighboring *** three native species could endure environmental stresses due to their distinctive ecophysiological *** play important roles in sustainable pastures production,recreation and *** suffer severe threat from many factors including;grazing,agriculture and invasive exotic *** analyzed the potential habitat of three native plant species in central Iran basing on the grid map with the resolution of *** used inventory records from field surveys,herbarium collections and 22 environmental factors to explore the environmental influences on given species distribution by Maximum entropy（Maxent） *** is a species distribution model that uses species occurrence and environmental data for predicting potential *** results of our study indicated species occurrence has strong correlation with environmental factors such as mean temperature of wettest season,elevation and precipitation of coldest *** evaluated the model accuracy by AUC（area under the receiver operating characteristic curve） based on an independent test data *** values indicated the high power of Maxent to create potential habitat map（***=0.988,***=0.927,***=0.923）.It is important to consider that AUC values tend to be lower for species that have broad distribution scope,such as *** *** suitable potential habitat distributions of the three species were predicted in the western and southwestern parts of rangelands in Isfahan *** comparisons of the actual distribution map of the three species with produced Maxent maps represent a good *** general,the model demonstrated that the occurrence of the given species

关键词： Astragalus caragana Astragalus cyclophyllon Astragalus podolobus environmental factors Maxent

Interactions between vegetation dynamic and edaphic factors in the Great Salt Desert of central Iran

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Journal of Arid Land 2021年第2期13卷 123-134页

作者： Hossein BASHARI Seyed Mehrdad KAZEMI Soghra POODINEH Mohammad R MOSADDEGHI mostafa tarkesh Seyed Mehdi ADNANI Department of Natural Resources Isfahan University of TechnologyIsfahan ***Iran Department of Soil Science College of AgricultureIsfahan University of TechnologyIsfahan ***Iran Forests and Rangelands Research Department Qom Agricultural and Natural Resources Research and Education CenterAgricultural ResearchEducation and Extension Organization(AREEO)Qom ***Iran

Investigating the relationships between vegetation dynamic and edaphic factors provide management insights into factors affecting the growth and establishment of plant species and vegetation communities in saline *** aim of this study was to assess the spatial variability of various vegetation communities in relation to edaphic factors in the Great Salt Desert,central *** vegetation communities were identified using the physiognomy-floristic *** and density of vegetation communities were determined using the transect plot *** soil samples were collected from major horizons of fifteen profiles in vegetation communities,and analyzed in terms of following soil physical and chemical characteristics:soil texture,soluble Na+concentration,sodium adsorption ratio(SAR),electrical conductivity(EC),pH,organic matter content,soluble Mg2+and Ca2+concentrations,carbonate and gypsum contents,and spontaneously-and mechanically-dispersible clay *** analysis was used to investigate the relationships between vegetation dynamic and edaphic *** generalized linear method(GLM)was used to find the plant species response curves against edaphic *** showed that plant species responded differently to edaphic factors,in which soluble sodium concentration,EC,SAR,gypsum content and soil texture were identified as the most discriminative edaphic *** studied plant species were also found to have different ecological requirements and tolerance to edaphic factors,in which Tamarix aphylla and Halocnemum strobilaceum were identified as the most salt-resistant species in the ***,the presence of Artemisia sieberi was highly related to soil sand and gypsum *** results implied that exploring the plant species response curves against edaphic factors can assist managers to lay out more appropriate restoration plans in similar arid areas.

关键词： desert generalized linear method mechanically-dispersible clay ordination plant species response curves spontaneously-dispersible clay